My experience is only with the older X495 diesel all wheel steer tractor, which had over 2500 hours on it when I sold it. Never had an overheating issue...
Are you guys cleaning the oil cooler at the same time you service the screens and the radiator fins??? Here is what the operator's manual for the X495 states -- and note the recommendation of 30 PSI air as a maximum for this cleaning:
When the dealer delivered my x758 this year, he mentioned to keep the screens clean to prevent overheating, so it’s a known issue. It’s only overheated once when mowing lots of leaves. I’m more attentive to it now and haven’t had a problem since. The tractor does like to suck in lots of debris on the screens by my legs.
Just spent my first five hours on my new 2020 C758. Fantastic mower and a real beast. We live on some very hilly property and have a vineyard. Rough terrain and not easy to mow. After the first two hours, my machine overheated. That is when I searched for this thread. Someone had mentioned making sure the screen behind the radiator is clean. I did that and everything was fine. An hour or so later it started to heat up again. Pulled over, put the mower in idle, cleaned the screen, and off I went. Took two minutes and this seems to relieve the problem. Our grass is quite dry and kicks up a lot of dust and dry grass that easily clogs the screens. If you live in this kind of environment, you will need to do this. Each time I cleaned it, the screen was at least half clogged with dust and grass and it is easy to see why the motor started to heat up.This machine needs to breathe.
How many bar is everyone seeing when it is "over heating"?
My X758 runs at 3, if it goes up to 4 which is seldom I will pull the inner screen and blow off with the leaf blower which turn out to be about every 5 hours of run time. Today it will be in the 90's and it will be fine other than my barefoot left foot gets toasted if I leave it at the end of the floor board for extended periods of time.
I run mine up to where there are 2 unlit bars on the graph. Then I clean it. Or after the mower PTO shuts off if I miss seeing it. I mow about 7 acres at a time and unless the grass is really green and wet I have to clean the screen 2 or 3 times per session.
It's best to stop periodically and clean the screens instead of waiting until the tractor shuts the PTO down in a safety mode to avoid engine damage. The preset temp at which the PTO shuts down is pretty high as I looked it up in the Technical Service Manual (I want to say it's between 220 and 225 degrees)
Also, as someone else mentioned, make sure to clean off the oil cooler if its a stand alone unit, like it is on newer machines. On the older machines, the lower part of the radiator was the oil cooler and once you got the hydro oil that hot, it was much harder to cool down and keep the engine cooler.
Keeping the screens clean makes the entire machine run cooler, which also keeps the operator cooler. If the screens on the outside of the tractor are covering with debris, keep brushing them clear as you can as every bit of air flow helps with cooling the machine.
Also, the machines do need to have the radiator washed clean of dirt and dust from time to time, with a careful use of a water hose. DO NOT use a power washer as the pressure can damage the radiator cooling fins and compromise the radiators function. Just use a regular garden hose and if you can, without the engine running, rinse the radiator from BACK to FRONT, pushing the dirt and debris out of the radiator. This means rinsing from the fan side through the radiator.
As always, be careful not to touch the aluminum fins or you will bend them and possibly damage them. They are fairly fragile.
Also, I have a special air and water radiator cleaning wands, just for these purposes. Here is a link to them. I bought them at a Mahindra dealer when I was in there picking up parts for my friends mower. One hooks to the air hose and the other to a water hose. Always clean out the radiator with air first as you want to remove as much dust and dirt as you can before getting the debris wet, as it is harder to remove once wet..........
I have an X754 that I have to keep an eye on the temperature gauge due to chaff blocking the air inlets. It's a result of the rear mounted radiator design and will happen with any model and engine type.
I had this problem with my X595 from the grass blowing out and getting on the deck. Then it would end up in the radiator. I got the anti blowout kit for the deck and have no problem overheating even mowing in 90 degree weather.